President Joe Biden on Tuesday announced a new effort to encourage more Americans to get Covid-19 vaccines, as the rates of new vaccinations drop and Covid-19 cases increase in some regions—largely fueled by the delta coronavirus variant.

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Biden announces new vaccination effort

In his announcement, Biden said the federal government would begin winding down its mass vaccination sites and shift its focus to other venues in areas with low vaccination rates.

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Specifically, the White House coronavirus response team plans to direct more Covid-19 vaccines to family doctors' offices and pediatricians' offices, hoping especially to reach children from ages 12 to 18.

The government will also continue to work with employers to ensure Covid-19 vaccines are available to employees at work or that employees receive paid time off to get vaccinated elsewhere.

The federal government will deploy more mobile clinics as well, Biden said, including at special events, places of worship, and "wherever we can find people gathered."

Biden also said the government will deploy "surge response teams" consisting of experts from across the government who will "help states that have particular problems prevent, detect, and respond to the spread of the delta variant among unvaccinated people in communities with low vaccination rates."

These teams will help expand Covid-19 testing, provide medicines for Covid-19 patients, deploy federal personnel to help with staffing, and utilize technical experts to investigate Covid-19 outbreaks, Biden said.

"Our fight against this virus is not over," Biden said. "Right now, as I speak to you, millions of Americans are still unvaccinated and unprotected. And because of that, their communities are at risk. Their friends are at risk. The people they care about are at risk. This is an even bigger concern because of the delta variant."

Covid-19 rates surge in some areas of the U.S.

According to CDC, 55% of the U.S. population and 67.1% of American adults have received at least one dose of a Covid-19 vaccine, while 47.5% of the U.S. population and 58.3% of American adults have completed all required vaccine doses.

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The White House said it anticipates that 160 million Americans will have completed their vaccine course by the end of this week, and that 70% of Americans 27 and older will have received at least one dose of a vaccine after data from the July 4 weekend has been collected.

However, the rate of new vaccine administration has been dropping, with just 0.87 million doses of vaccines being administered per day as of Tuesday, compared with 3.38 million doses on April 13.

And in some areas of the United States, vaccination rates have been especially low, allowing the coronavirus to surge, according to data from Johns Hopkins University.

For example, in Alaska and Arkansas, Covid-19 cases more than doubled over the past week, and case rates in South Carolina and Kansas have increased by over 50%.

According to USA Today, one area of Missouri—a state where just 39.4% of residents are fully vaccinated—saw Covid-19 hospitalizations increase by nearly 30% of the July 4 weekend, leading to a temporary shortage in ventilators.

CDC Director Rochelle Walensky said that around 1,000 counties in the United States have less than 30% of their residents vaccinated.

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"In some of these areas we are already seeing increasing rates of disease," Walensky said. "As the delta variant continues to spread across the country, we expect to see increased transmissions in these communities, unless we can vaccinate more people."

Delta variant drives a greater share of cases worldwide

The shift in U.S. vaccine strategy comes as new data out of Israel found that more than half of all Covid-19 cases in the country last week occurred in people who had been fully vaccinated against Covid-19. Currently, more than 80% of Israel's population has been fully vaccinated with the Pfizer-BioNTech Covid-19 vaccine.

Israel's Health Ministry said the vaccine showed about 64% effectiveness in preventing a Covid-19 infection during the current outbreak, a drop from 94% before the outbreak. Despite this drop in overall effectiveness, the vaccine was still 94% effective at preventing severe Covid-19.

And since mid-June, Israel has reported just two deaths from Covid-19, despite a rise in case rates.

Eyal Leshem, director of the Sheba Hospital's Center for Travel Medicine and Tropical Diseases, said the data is in line with other evidence from around the world showing the Pfizer-BioNTech vaccine is less effective against the delta variant.

And public health authorities warn the delta variant is gaining ground in the United States as well. According to a CDC spokesperson, the delta variant caused 30.4% of U.S. cases in the two weeks before June 19. By the end of the following two weeks, that share had surged to 51.7%. (President Biden remarks, 7/6; Chalfant/Samuels, The Hill, 7/6; Shear/Weiland, New York Times, 7/6; Keith, NPR, 7/6; Schnell, The Hill, 7/6; Weixel, The Hill, 7/6; McArdle, Washington Post, 7/6; Lieber, Wall Street Journal, 7/6; Polus, The Hill, 7/6; Lim/Banco, Politico Pro, 7/6)